Now the problem which Bessemer set before himself was to find out how to make a metal which could be cast like cast iron yet should be as strong and tough as wrought iron. After a little experimenting, by a happy inspiration, he hit upon the idea of blowing air through a mass of molten pig iron, thereby burning out the carbon, just as is done in the puddling process, only much quicker and with less labour. By this means he produced a metal with less carbon than cast iron and more than wrought iron, a sort of intermediate state between the two, and to his joy he found that this "Bessemer steel" could be cast like cast iron yet had strength and toughness equal to if not superior to that of wrought iron. Moreover, it was homogeneous and when rolled did not possess the troublesome grain characteristic of wrought iron. Having thus found the way to make this new and desirable metal, Bessemer encountered a great disappointment, so great that it would have entirely beaten many men. He made samples of steel and submitted them to experts in iron manufacture. Everyone thought them admirable and many large iron works were induced by them to make arrangements with Bessemer for the right to use his process. His name was already famous and it seemed as if a new fortune was made, when, to his alarm, he learned that wherever it was tried except in his own works, the process was a miserable failure. Instead of being at the end of his labours he was just at the beginning. It turned out that the particular iron which he happened to buy and use at his own works was particularly free from an impurity which is, generally speaking, a great nuisance in iron, namely, phosphorus. It was pure accident which had led him to use this iron: it happened to be the kind he could purchase most easily in the small quantities needed for his experiments but it led him into a great difficulty, for other people, after paying him for the right to use his process and after spending large sums on the requisite plant, found themselves unable to make the steel because of the phosphorus in their iron and finding themselves unable to make a success were inclined to write him down a fraud. As it turned out, after much labour on Bessemer's part, it was due to the presence of tiny percentages of phosphorus in most of the iron that is produced. After much trouble he was able to induce certain owners of blast-furnaces to make, by special methods, a kind of pig iron practically free from phosphorus and therefore suitable for his process. This special pig iron was known as Bessemer Pig Iron. A little later a new inventor, a Welshman, Thomas by name, overcame the difficulty in another way, but to explain that I must first describe the Bessemer Converter, the special apparatus designed by Bessemer for making his steel.